Vic Gundotra, a key executive at Google who helped to create Google+, is leaving the company, he announced on Thursday.

Gundotra worked at Google for nearly eight years, spearheading the development of Google+, as well as Google I/O, the company's annual conference for developers. For a time Google's mobile apps also fell under his purview, including services like turn-by-turn directions.

"I have been incredibly fortunate to work with the amazing people of Google," he said in a Google+ post announcing his departure.

He did not say exactly why he was leaving. A Google spokesman said the change takes effect immediately.

Gundotra's departure could create challenges in Google's efforts to attract users to Google+, which has struggled to compete against the likes of Facebook and Twitter. Google+ largely exists as the central platform for managing users' identity across Google's services like YouTube and Gmail. People can also use it for sharing content like they do on Facebook, but Facebook has many more active users.

To attract new users, last year Google rolled out a range of new photo editing tools for Google+.

Google CEO Larry Page, in a Google+ post of his own, said that the company would continue to build new experiences for Google+. "We'll continue working hard," he said.

Google would not comment directly on who might replace Gundotra, though a report in Re/code said that David Besbris, VP of engineering at Google, has been picked by Page to replace him. Besbris was part of the team that built Google+, according to his own Google+ profile.